Field of Disclosure
The following relates generally to wireless communication, and more specifically to radio resource management (RRM) measurement and reporting for license assisted access (LAA).
Description of Related Art
Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems, (e.g., a Long Term Evolution (LTE) system). A wireless multiple access communications system may include a number of base stations, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE).
In an LTE or LTE-Advanced (LTE-A) network, a base station and a UE may communicate over dedicated frequency spectrum that is licensed to the network operator. A licensed operator network (e.g., cellular network, etc.) may be known as a public land mobile network (PLMN). With increasing data traffic in cellular networks that use dedicated (e.g., licensed) radio frequency bands, offloading at least some data traffic to unlicensed or shared radio frequency spectrum may enhance data transmission capacity and efficient use of resources. Unlicensed and shared radio frequency spectrum may also provide service in areas where access to a dedicated radio frequency spectrum is unavailable. Unlicensed spectrum generally refers to spectrum available for use without a license and is typically subject to technical rules regarding access and transmitted power. Shared spectrum generally refers to spectrum that is licensed to one or more operators but follows some device coexistence procedures (e.g., a licensed radio frequency spectrum band having more than one licensed operator, a licensed radio frequency spectrum band having a prioritized operator but providing for opportunistic sharing of resources, etc.).
A listen before talk (LBT) procedure may be used for contention resolution for access to shared frequency resources of licensed or shared frequency spectrum without pre-coordinated resource allocation. An LBT procedure may include performing a clear channel assessment (CCA) procedure to determine whether a shared channel is available. When it is determined that the shared channel is available, a device may transmit a signal to reserve the channel before data transmissions. Other devices may monitor for the reservation signal to detect transmissions, and may also monitor the shared channel using energy detection to determine whether the shared channel is busy or free.
Operation using LTE signal waveforms over the shared radio frequency spectrum may be called LTE-Unlicensed (LTE-U) operation, and an LTE device supporting LTE-U operation may be called an LTE-U device. Operation using LTE/LTE-A carriers in unlicensed or shared frequency spectrum may be used in a standalone operation mode where an LTE/LTE-A carrier in shared spectrum can be used as a primary cell for a UE or in a licensed assisted access (LAA) mode where a UE is configured for carrier aggregation with a primary cell in a licensed spectrum band and one or more LTE/LTE-A secondary cells in unlicensed or shared frequency spectrum.
In LTE/LTE-A networks, radio resource management (RRM) includes procedures for managing radio resources including scheduling, power control, handover, and load-balancing. RRM procedures performed by UEs include measurement and reporting of serving cells and neighbor cells for service continuity and resource management. For example, cell measurements may be used to determine when to handover UEs or for channel selection for serving cells. Because cells in unlicensed or shared frequency spectrum may be subject to LBT procedures, RRM cell measurement and reporting procedures designed for dedicated spectrum may provide insufficient information to efficiently allocate resources among unlicensed or shared frequency spectrum.